(a) Field of the Invention
The present invention relates to an adapter device for securement to the output rotary drive of a drill whereby to impart a rotary, rotary and impact, or an impact force only to a bit secured to the adapter.
(b) Description of Prior Art
Adapters are known to generate percussion forces to a drilling bit such as that disclosed in U.S. Pat. No. 3,149,681. In this patent, the adapter is mountable on a power drill to produce rotation only or a combined rotation and hammering. To add the hammering only mode of operation, it would be necessary to completely redesign the concept of the cam, the input connector, and the output connector. The cam in the aforementioned patent allows only one direction of rotation. Also, a ball-type cam follower is used and it has the disadvantage of point loading which results in excessive wear, and is not suitable for applications involving impact loads.
Another disadvantage of prior art, such as the patent mentioned above, is that the impact strength is achieved by positioning an adjusting device to obtain a certain impact force. Thus, a constant impact force is obtained and the user is not in full and immediate control over the hammering function of the adapter. There is a need to provide impact strength by simply varying the pressure applied on the tool by the user, which need is provided by Applicant's invention.
In the prior art, either two types of cams are generally used, (a) the unidirectional impact type similar to the one used in the above-referred to patent and (b) the bi-directional reciprocating type. The former of the two cams is unidirectional and as such cannot be used in drills capable of reverse rotation. The latter, although bi-directional, produces reciprocating action rather than crisp impacts.
It is a feature of the present invention to substantially overcome the above disadvantages of the prior art and to provide an adapter which is capable of producing a rotary, rotary and impact, or impact forces only, on a bit secured thereto.
According to a further feature of the present invention, there is provided an adapter device for securement to an output rotary drive of a drill and wherein the user varies the impact strength by simply varying the pressure he applies on the drill.
Another feature of the present invention is to provide an adapter device for securement to an output rotary drive of a drill and which is capable of providing a hammering only mode to extend the use of the adapter to other applications like chiseling and general impacting applicators (i.e. hammering).
Another feature of the present invention is to provide an adapter device for securement to an output rotary drive of a drill and which adapter comprises a bi-directional true impact cam.
Another feature of the present invention is to provide an adapter device which is relatively simple to construct, use and repair.
According to the above features, from a broad aspect, the present invention provides an adapter device for securement to an output rotary drive of a drill. The adapter comprises a housing having an input connection means securable to the rotary drive. An output connector is also provided. A fixed mode cam is immovably secured with respect to the housing. A displaceable floating cam is provided intermediate the input connection means and a displaceable keying element. The floating cam is displaceable in and out of engagement with the keying element. Selective adjustment means is provided to displace the keying element in and out of engagement with the fixed mode cam and the floating cam whereby the input connection means can impart a rotary, rotary and impact, or impact forces to the output connector.